PHILADELPHIA Virginia Gov. James S. Gilmore III, king of the car-tax cut, took his message of lower taxes to the Republican National Convention last night."The temptation in government is to spend every available tax dollar and reach for more. A century of such taxing and spending has left the American people clamoring to preserve their individual liberty to keep more of the money they earn," Mr. Gilmore said.His five-minute speech was one of the highlights of the 8 p.m. hour at the convention, whose theme was "keeping America prosperous and protecting retirement security."Mr. Gilmore's speech was delivered too early to be covered by most national networks, which opted to air the convention from 10-11 p.m.The similarities between Mr. Gilmore and Texas Gov. George W. Bush, the presumptive Republican presidential nominee, are striking. Both won their state elections by campaigning on cutting taxes, but increasing education spending and both men have followed through.Yesterday, Mr. Gilmore stressed that, even more than tax cuts, education is the party's Holy Grail issue for the 21st century.Still, he left no doubt that tax cuts are his favorite issue."In Virginia, I was elected on a promise to cut the tax on cars. I kept that promise, and the people appreciate it. Tax cuts matter to every American, especially the working poor," he said, evoking a significant round of applause from the crowd.The governor even tried a little bit of humor in his speech, quipping about Ben Franklin's death-and-taxes maxim, "Of course Ben never thought his words would become the slogan of the modern Democratic Party."Many Republicans say Mr. Gilmore has inherited from Jack Kemp the mantle of leadership for the party's tax-cut wing.